Edges of various panels including sawn lumber, plywood, composition material, particularly in cabinet making, require covering with strips or bands of a material to improve appearance, conceal irregularities or add durability to the manufactured product.
U.S. Pat. No. 4,222,812 to Duewel discloses an edge banding machine which is table mounted. The machine utilizes a heater for heating hot air which in turn is blasted against a preglued edge band strip coated with high viscosity hot melt glue, whereupon after the glue is melted, the banding material is pressed against the edge of the panel as the glue cures. In such machine, the panel is moved longitudinally in a relatively straight line in contact with a spindle which positions the edge band relative to the edge of the panel and wherein the panel is pressed so as to sandwich the edge band between the spindle and the panel edge with the melted glue surface in contact with the panel edge.
U.S. Pat. No. 4,067,762 to Rhoads discloses a hand held, i.e. portable edge bander which includes a thermostatically controlled electric heater for melting preglued tape-like trim whereby the tape is preheated by the heater as the operator moves the machine along the edge of the panel to be covered. The tape is stored above the working surface of the hand held implement and transported by a series of rollers to the underside of a plate, at which point it is bonded onto the working surface edge.
Such apparatus have not proven satisfactory since the heaters tend to scorch the banding material, cause bubbling of the adhesive if the period of contact is excessive, and require that the workpiece be moved through the apparatus or the apparatus move relative to the workpiece at a more or less constant rate, requiring a skilled operator. Further, there is difficiulty in readily stopping or starting the procedure.
Rather complicated, large and expensive machinery has been developed in which the adhesive is melted and applied in liquid form to the edge of the panel to be banded and which involve mechanisms for positively driving both the panel to be banded and the band or strip itself. Such machinery, in addition to being expensive, involves the difficulty of synchronizing the movement of the panel being edge-banded to the band material itself. Further, the adhesive, which is applied in liquid form, immediately prior to the application of the edge band, requires significant drying or curing time which is both time consuming and expensive, and often the adhesive seeps between the band and the panel edge resulting in contamination of the machine parts and spoiling the decorative appearance of the banded panel. One such machine is sold under the trademark HOLZ-HER and is manufactured by the Carl M. Reich Maschinfabrik Gmbh, Nurtingen, West Germany.
In an effort to assist the cabinetmaker in applying hot melt adhesive to a panel edge or to a band prior to bonding to the panel edge, or both, the Minnesota Mining and Manufacturing Company of St. Paul, Minn., has developed a hot melt adhesive applicator gun under the trademark POLYGUN II which is effective in applying JET-MELT brand hot melt adhesive. The adhesive, which is a 100 percent solid, solvent-free, thermoplastic resin, becomes fluid when heated, adequately wets the substrate, and when cooled, hardens without chemical change, forming a strong bond to most wood surfaces such as wood, plastic, foam, fabric, cardboard, ceramics, plastic, etc. The adhesive applicator gun is light weight, has a true gun handle with a trigger mechanism at the leading edge of the handle beneath the electrical melting system, and is characterized by a straight through design nozzle which discharges the hot melt adhesive in liquid form through a small diameter bore within the nozzle.
It is, therefore, a primary object of the present invention to provide an improved, low cost, and simplified apparatus for applying a continuous band of material to the edge of a panel and which incorporates within that apparatus a hot melt adhesive applicator gun such as the commercially available applicator gun of the Minnesota Mining and Manufacturing Company.
It is a further object of the present invention to provide an improved hot melt plastic gun type panel edge banding apparatus in which the gun is carried by a floating mount to pressure the extrusion tip into substrate contact, insures a thin glue line on the finished product, reduces glue consumption and eliminate product clean-up, and which eliminates the need for automatic feed of either the panel or band or automatic trimming of the band subsequent to band application.
It is a further object of the present invention to provide an improved hot melt adhesive gun type panel edge banding apparatus characterized by a hand held device featuring a material magazine and edge guide that can be quick connected or disconnected to and from a table module, and wherein hand movement of the panel across the table top effects in a simplified and direct manner operation of the hot melt adhesive applicator gun and controlled synchronous frictional movement of the band into contact with the panel edge downstream of the adhesive extrusion area.